<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div {
            height: 300px;
        }
        .section1 {
            background-image: url("image/a1.jpg");
            background-repeat: no-repeat;
            background-position: top center;
            background-attachment: fixed;
        }
        .section2 {
            background-image: url("image/a2.jpg");
            background-repeat: no-repeat;
            background-position: top center;

            background-attachment: fixed;
        }
        .section3 {
            background-image: url("image/a3.jpg");
            background-repeat: no-repeat;
            background-position: top center;

            background-attachment: fixed;
        }
    </style>
</head>
<body>
<div class="section1"></div>
<br>
<br>
<br>
<br>
<br>
<br><br>
<br>
<br>
<br>
<br>
<br>
<div class="section2"></div>
<br>
<br>
<br>
<br>
<br>
<br><br>
<br>
<br>
<br>
<br>
<br>
<div class="section3"></div>
<br>
<br><br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
</body>
</html>